Recently, self-supervised learning (SSL) methods have been used in pre-training the segmentation models for 2D and 3D medical images. Most of these methods are based on reconstruction, contrastive learning and consistency regularization. However, the spatial correspondence of 2D slices from a 3D medical image has not been fully exploited. In this paper, we propose a novel self-supervised alignment learning framework to pre-train the neural network for medical image segmentation. The proposed framework consists of a new local alignment loss and a global positional loss. We observe that in the same 3D scan, two close 2D slices usually contain similar anatomic structures. Thus, the local alignment loss is proposed to make the pixel-level features of matched structures close to each other. Experimental results show that the proposed alignment learning is competitive with existing self-supervised pre-training approaches on CT and MRI datasets, under the setting of limited annotations.

最近，自监督学习方法已被用于对二维和三维医学图像的分割模型进行预训练。本文提出了一种新的自监督对齐学习框架来预训练医学图像分割的神经网络，其中包括了一个全新的局部对齐损失和全局位置损失。实验结果表明，该对齐学习方法在有限标注的CT和MRI数据集上与现有的自监督预训练方法具有竞争力。

医学图像分割的自我监督对齐学习